First, Twisted doesn't always use the BSD sockets API; the Windows IOCP reactor, especially, starts off with the socket() function, but things go off in a different direction pretty quickly from there.
Hmm. Are you saying it doesn't use listen, connect, bind, send, recv? To me, that's the core of BSD sockets. I can understand it doesn't use select(2).
So it's perfectly fine to introduce yourself to networking via Twisted, and many users have done just that. If you're using it idiomatically, you should never encounter a socket object or file descriptor poking through the API anywhere.
And that's all fine. I still claim that you have to *understand* sockets in order to use it properly. By this, I mean stuff like "what is a TCP connection? how is it established?", "how is UDP different from TCP?", "when data arrives, what layers of software does it go through?", "what is a port number?", etc.
Second, it makes me a little sad that it appears to be folk wisdom that Twisted is only for servers. A lot of work has gone into making it equally appropriate for clients. This is especially true if your client has a GUI, where Twisted is often better than a protocol-specific library, which may either be blocking or have its own ad-hoc event loop.
I think that's because many of the problems that Twisted solves don't exist in many of the client applications - in particular, you often don't have many simultaneous connections. GUI apps may be the interesting special case, but I expect that people dealing with these rather use separate threads.
I don't have an opinion on the socket HOWTO per se, only on the possibility of linking to Twisted as an alternate implementation mechanism. It really would be better to say "go use Twisted rather than reading any of the following" than "read the following, which will help you understand Twisted".
Wouldn't you agree that Twisted is very difficult to learn, and thus much heavier than sockets? And I don't blame the Twisted API for that, but rather the mental model of overlapping activities that people have severe problems with. Regards, Martin